1. Field of the Invention
The present invention relates to a system for securing an item such as a shelf or support hook to a column, and more particularly, to a system including the column or post and a single element constituted by two pieces which are loosely coupled yet cooperate so that, when secured to the post, the resistance of the element to a downward force increases with an increase in the force exerted.
Known shelving systems are disclosed in U.S. Pat. Nos. 3,424,111 and 3,757,705 both to Louis Maslow and assigned to the assignee of the subject invention. These shelving systems include a plurality of vertically extending columnar support posts each having a series of uniformly spaced annular grooves formed on its outer surface. A sleeve unit, one for each location at which an element is to be supported, is constructed of two complementary partially tubular members adapted to encircle a corresponding post. Each sleeve unit is provided with a raised annular rib, formed on its inner surface and which may engage any one of the annular grooves on the post.
The outer surface of each sleeve unit is shaped as a conical frustum and its inner surface is generally shaped as a right cylinder so that the wall of the sleeve unit is thickest at the bottom.
Each element to be supported, such as a shelf, is provided with a collar. Each of these collars has a conical frustum shaped inner wall adapted to nest on the outer surface of the sleeve units. Accordingly, application of a load to the shelf causes each collar to press downwardly on its associated sleeve unit with their respective conical surfaces in tight wedging engagement.
The sleeve is positioned along the length of the post so that the annular rib engages one annular groove on the post. The engagement of the rib and groove together with the frictional engagement between the outer wall of each support post and the inner surface of the sleeve units prevent downward vertical movement of the sleeve units, maintaining the shelf in a stable, supported position. Moreover, as the load on the shelf is increased, the radially inwardly directed force resulting from the engagement of the conical wall of each collar and the mating surface of each sleeve unit increases, thus increasing the frictional force between the sleeve units and the support posts. While the system of the Maslow Patents has proven to be quite satisfactory for its intended purposes, it has been observed that the two-part sleeve is not captured with either a collar on the shelf or a corner post. Therefore when the system is disassembled for shipment or storage the sleeve components, which are relatively small, may be lost or misplaced.
2. Description of the Prior Art
Systems for securing items, such as shelves, to vertical posts, have taken many forms in prior art. One type of system for securing a shelf to a post, and deemed relevant to the present invention, is illustrated in U.S. Pat. No. 3,657,598 (Kesilman, et al.) and includes a sleeve which is mounted on the corner of a shelf. The sleeve has a screw extending inwardly in contact with the post about which the sleeve is mounted. When the screw is tightened, it pulls the opposite portion of the sleeve toward the post while fitting tightly against the post itself to increase the radial force holding the shelf in position. If the shelf is to be fixed at predetermined positions, the post may have detents or through-holes for receiving the tightening screw. If no detents or through-holes are provided, the screw can mar and eventually damage the posts. Furthermore, overtightening the screw may strip its threads, resulting in insecure positioning of the shelf on the post.
A commercially available product sold under the name "Cidelcem," which provides for unrestricted positioning of a shelf on vertically extending corner posts, includes a collar fixed to the shelf and having a conical inner wall that terminates at its lower extremity in a cylindrical thread. A conical inner ring, encircling a corner post, mates with the inner wall of the collar and is urged into wedging engagement therewith by a nut threaded into the cylindrical thread in the inner wall of the collar. The wedging action thus created collapses the ring into engagement with the post.
However, in this system, it is difficult to tighten the nut sufficiently to secure the shelving at a fixed location on the post. That is, when a vertical load is applied, the shelving may slip on the posts.
Other less relevant shelving systems are disclosed in U.S. Pat. Nos. 3,245,365 (Doherty); 3,344,756 (Kelson); and 3,182,846 (LaKaff). Still other structures for supporting a member on a vertical column are shown in U.S. Pat. Nos. 2,032,023 (Lisicke); 3,458,234 (Bates); 2,705,119 (Ingwer); 2,388,056 (Hendricks); 2,716,533 (Freeman); 2,947,556 (Wenger) French Pat. No. 855,715 (Pollack); and German Patentschrift No. 135,665. None of these, however, is as pertinent to the subject invention as those discussed in greater detail above.